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A term newborn with a right-sided CDH and severe pulmonary hypertension with systemic hypotension required veno-arterial ECMO. Despite appropriate cannulas size, high drainage pressure exceeding 60 mmHg was needed to maintain an ECMO flow at 120 ml/kg/min. Pericardial tamponade and misplacement of the venous cannula within the azygos vein were detected. Open thorax surgery was performed, and the cannula was repositioned. Postoperative X-rays showed an anomalous tip position of the cannula, suggesting the kinking inside the right atrium (Fig. 1). Reintervention was needed to restore the cannula. Cannula problems complicate about 12.8% of all neonatal respiratory ECMO1. Both cannula malposition and kinking can affect the proper functioning of the ECMO support, and they should be carefully ruled out anytime suboptimal venous drainage and insufficient ECMO flow are experienced2.
Nevertheless, their diagnosis can be challenging, and both X-ray and echocardiography are essential tools3,4. In particular, incidental azygos vein cannulation represents a possible rare ECMO complication in right-sided CDH and should always be kept in mind in this specific population3. The decision to reposition or replace the cannula is mandatory, although not risk-free, in case of inadequate venous drainage or case of possible cardiac or vessel perforation5.
References
  1. ELSO. ELSO Registry International Summary . ELSO 2019.
  2. Mayer A, Raffaeli G, Schena F, et al . Successful extracorporeal membrane oxygenation after incidental azygos vein cannulation in a neonate with right-sided congenital diaphragmatic hernia, interruption of inferior vena cava and azygos continuation. Front Pediatr2019;7:444.
  3. Thomas TH, Price R, Ramaciotti C, Thompson M, Megison S, Lemler MS. Echocardiography, not chest radiography, for evaluation of cannula placement during pediatric extracorporeal membrane oxygenation.Pediatr Crit Care Med 2009;10:56–9.
  4. Fisher JC, Jefferson RA, Kuenzler KA, Stolar CJ, Arkovitz MS. Challenges to cannulation for extracorporeal support in neonates with right-sided congenital diaphragmatic hernia. J Pediatr Surg2007;42:2123–8.
  5. Byrnes J, Prodhan P, Imamura M, Frazier E. Accidental azygos vein extracorporeal membrane oxygenation cannulation in a neonate with premature closure of the ductus arteriosus. ASAIO J2011;57:344–5.